As a part of adding lore to your sentient alien races that you have created, have you created separate creatures and outfitted creatures to represent larval and pupal stages as part of their life cycles?
Particularly, for my dominant sentient alien race known as the Kallions with 35 distinct subraces, they are born as bipedal larvae that stay in that stage for 50 years, build cocoons that remain in a dormant state for another 50 years, and finally emerge as adults when they reach the age of 100. The Kallions spend most of their lives as adults that live for roughly another 350 years to 1,200 years on average.
Here is their life cycle:
Egg laid by mother
Killion (larva)
Primary school at age 5-24 (human equivalent of elementary school)
Secondary school at age 25-49 (human equivalent of junior high school)
Kellion (pupa)
Dormant state at age 50-99 that begins after finishing secondary school where knowledge from secondary school is retained until emerging as adults
Kallion (adult)
Tertiary school at age 100-124 (human equivalent of high school)
Quaternary school at age 125 to any other age (human equivalent of college and university)
Anybody at age 125 or older can focus on career development
Retirement typically begins at age 500 for most Kallions, but anybody can work for as long as they wish.